Artigos de revistas: "Optical Atomic Magnetometry"

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Li, Rujie, Christopher Perrella e André Luiten. "Enhancing the sensitivity of atomic magnetometer with a multi-passed probe light". Applied Physics Letters 121, n.º 17 (24 de outubro de 2022): 172402. http://dx.doi.org/10.1063/5.0119222.

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Atomic magnetometry has spectacular magnetic field sensitivity at room temperature. Here, we theoretically and experimentally investigate the benefits of a multi-pass cell in magnetometers using nonlinear magneto-optical rotation interrogation. Our theoretical analysis shows that there is an improvement in the signal-to-noise ratio (SNR) and consequently on the magnetic field sensitivity by carefully choosing the number of passes through the medium. In our specific case, we experimentally demonstrate a 160% enhancement in the magnetometer sensitivity by using a triple-pass cell, and it is consistent with our analysis on the SNR. This work provides a pathway to evaluate the benefits of multi-pass cells in high-performance atomic magnetometers.

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Song, Shupei, Xining Li, Xinyi Zhu, Bao Chen, Zhifei Yu, Nanyang Xu e Bing Chen. "An integrated and scalable experimental system for nitrogen-vacancy ensemble magnetometry". Review of Scientific Instruments 94, n.º 1 (1 de janeiro de 2023): 014703. http://dx.doi.org/10.1063/5.0125441.

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Nitrogen-vacancy (NV) centers in diamond are extremely promising solid-state spin quantum sensors for magnetic field in recent years. The rapid development of NV-ensemble magnetometry has put forward higher requirements for high-speed data acquisition, real-time signal processing and analyzing, etc. However, the existing commercial instruments are bulky and expensive, which brings extra complexity to the weak magnetic field detection experiment and hinders the practicality and miniaturization of NV-ensemble magnetometry. Here, we report on an integrated and scalable experimental system based on a field-programmable-gate-array (FPGA) chip assisted with high-speed peripherals for NV-ensemble magnetometry, which presents a compact and compatible design containing high-speed data acquisition, oscilloscopes, signal generator, spectrum analyzer, lock-in amplifier, proportional-integral-derivative feedback controller, etc. To verify its applicability and reliability in experiments, various applications, such as optical magnetic resonance detection, optical cavity locking, and lock-in NV magnetometry, are conducted. We further realize the pump-enhanced magnetometry based on NV center ensembles using the optical cavity. Through the flexible FPGA design approach, this self-developed device can also be conveniently extended into atomic magnetometer and other quantum systems.

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Orzechowska, Zuzanna, Mariusz Mrózek, Wojciech Gawlik e Adam Wojciechowski. "Preparation and characterization of AFM tips with nitrogen-vacancy and nitrogen-vacancy-nitrogen color centers". Photonics Letters of Poland 13, n.º 2 (30 de junho de 2021): 28. http://dx.doi.org/10.4302/plp.v13i2.1095.

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We demonstrate a simple dip-coating method of covering standard AFM tips with nanodiamonds containing color centers. Such coating enables convenient visualization of AFM tips above transparent samples as well as using the tip for performing spatially resolved magnetometry. Full Text: PDF ReferencesG. Binnig, C. F. Quate, C. Gerber, "Atomic Force Microscope", Phys. Rev. Lett. 56, 930 (1986). CrossRef F .J. Giessibl, "Advances in atomic force microscopy", Rev. Mod. Phys. 75, 949 (2003). CrossRef S. Kasas, G. Dietler, "Probing nanomechanical properties from biomolecules to living cells", Eur. J. Appl. Physiol. 456, 13 (2008). CrossRef C. Roduit et al., "Stiffness Tomography by Atomic Force Microscopy", Biophys. J. 97, 674 (2009). CrossRef L. A. Kolodny et al., "Spatially Correlated Fluorescence/AFM of Individual Nanosized Particles and Biomolecules", Anal. Chem. 73, 1959 (2001). CrossRef L. Rondin et al., "Magnetometry with nitrogen-vacancy defects in diamond", Rep. Prog. Phys. 77, 056503 (2014). CrossRef C. L. Degen, "Scanning magnetic field microscope with a diamond single-spin sensor", Appl. Phys. Lett. 92, 243111 (2008). CrossRef J. M. Taylor et al., "High-sensitivity diamond magnetometer with nanoscale resolution", Nat. Phys. 4, 810 (2008). CrossRef J. R. Maze et al., "Nanoscale magnetic sensing with an individual electronic spin in diamond", Nature 455, 644 (2008). CrossRef L. Rondin et al., "Nanoscale magnetic field mapping with a single spin scanning probe magnetometer", Appl. Phys. Lett. 100, 153118 (2012). CrossRef J. P. Tetienne et al., "Nanoscale imaging and control of domain-wall hopping with a nitrogen-vacancy center microscope", Science 344, 1366 (2014). CrossRef R. Nelz et al., "Color center fluorescence and spin manipulation in single crystal, pyramidal diamond tips", Appl. Phys. Lett. 109, 193105 (2016). CrossRef G. Balasubramanian et al., "Nanoscale imaging magnetometry with diamond spins under ambient conditions", Nature 455, 648 (2008). CrossRef P. Maletinsky et al., "A robust scanning diamond sensor for nanoscale imaging with single nitrogen-vacancy centres", Nat. nanotechnol. 7, 320 (2012). CrossRef L. Thiel et al., "Quantitative nanoscale vortex imaging using a cryogenic quantum magnetometer", Nat. nanotechnol. 11, 677 (2016). CrossRef F. Jelezko et al., "Single spin states in a defect center resolved by optical spectroscopy", Appl. Phys. Lett. 81, 2160 (2002). CrossRef M. W. Doherty et al., "The nitrogen-vacancy colour centre in diamond", Phys. Rep. 528, 1 (2013). CrossRef C. Kurtsiefer, S. Mayer, P. Zarda, H. Weinfurter, "Stable Solid-State Source of Single Photons", Phys. Rev. Lett. 85, 290 (2000). CrossRef A. Gruber, A. Dräbenstedt, C. Tietz, L. Fleury, J. Wrachtrup, C. Von Borczyskowski, "Scanning Confocal Optical Microscopy and Magnetic Resonance on Single Defect Centers", Science 276, 2012 (1997). CrossRef F. Dolde et al., "Electric-field sensing using single diamond spins", Nat. Phys. 7, 459 (2011). CrossRef K. Sasaki et al., "Broadband, large-area microwave antenna for optically detected magnetic resonance of nitrogen-vacancy centers in diamond", Rev. Sci. Instrum. 87, 053904 (2016). CrossRef A. M. Wojciechowski et al., "Optical Magnetometry Based on Nanodiamonds with Nitrogen-Vacancy Color Centers", Materials 12, 2951 (2019). CrossRef I. V. Fedotov et al., "Fiber-optic magnetometry with randomly oriented spins", Opt. Lett. 39, 6755 (2014). CrossRef

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Li, Bei-Bei, Jan Bílek, Ulrich B. Hoff, Lars S. Madsen, Stefan Forstner, Varun Prakash, Clemens Schäfermeier, Tobias Gehring, Warwick P. Bowen e Ulrik L. Andersen. "Quantum enhanced optomechanical magnetometry". Optica 5, n.º 7 (12 de julho de 2018): 850. http://dx.doi.org/10.1364/optica.5.000850.

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Fatemi, Fredrik K., e Mark Bashkansky. "Spatially resolved magnetometry using cold atoms in dark optical tweezers". Optics Express 18, n.º 3 (19 de janeiro de 2010): 2190. http://dx.doi.org/10.1364/oe.18.002190.

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Dyakonov, Vladimir, Hannes Kraus, V. A. Soltamov, Franziska Fuchs, Dmitrij Simin, Stefan Vaeth, Andreas Sperlich, Pavel Baranov e G. Astakhov. "Atomic-Scale Defects in Silicon Carbide for Quantum Sensing Applications". Materials Science Forum 821-823 (junho de 2015): 355–58. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.355.

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Atomic-scale defects in silicon carbide exhibit very attractive quantum properties that can be exploited to provide outstanding performance in various sensing applications. Here we provide the results of our studies of the spin-optical properties of the vacancy related defects in SiC. Our studies show that several spin-3/2 defects in silicon carbide crystal are characterized by nearly temperature independent axial crystal fields, which makes these defects very attractive for vector magnetometry. The zero-field splitting of another defect exhibits on contrast a giant thermal shift of 1.1 MHz/K at room temperature, and can be used for temperature sensing applications.

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Maayani, Shai, Christopher Foy, Dirk Englund e Yoel Fink. "Distributed Quantum Fiber Magnetometry". Laser & Photonics Reviews 13, n.º 7 (17 de maio de 2019): 1900075. http://dx.doi.org/10.1002/lpor.201900075.

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Zhang, Qiaolin, Hui Sun, Shuangli Fan e Hong Guo. "High-sensitivity optical Faraday magnetometry with intracavity electromagnetically induced transparency". Journal of Physics B: Atomic, Molecular and Optical Physics 49, n.º 23 (18 de novembro de 2016): 235503. http://dx.doi.org/10.1088/0953-4075/49/23/235503.

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Li, Bei-Bei, George Brawley, Hamish Greenall, Stefan Forstner, Eoin Sheridan, Halina Rubinsztein-Dunlop e Warwick P. Bowen. "Ultrabroadband and sensitive cavity optomechanical magnetometry". Photonics Research 8, n.º 7 (3 de junho de 2020): 1064. http://dx.doi.org/10.1364/prj.390261.

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Belfi, J., G. Bevilacqua, V. Biancalana, Y. Dancheva e L. Moi. "All optical sensor for automated magnetometry based on coherent population trapping". Journal of the Optical Society of America B 24, n.º 7 (15 de junho de 2007): 1482. http://dx.doi.org/10.1364/josab.24.001482.

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Li, Siran, Danyue Ma, Kun Wang, Yanan Gao, Bozheng Xing, Xiujie Fang, Bangcheng Han e Wei Quan. "High sensitivity closed-loop Rb optically pumped magnetometer for measuring nuclear magnetization". Optics Express 30, n.º 24 (16 de novembro de 2022): 43925. http://dx.doi.org/10.1364/oe.473654.

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Rb optically pumped magnetometer (OPM) based on electron paramagnetic resonance (EPR) show advantages to measure the nuclear magnetization and have succeeded in fundamental physics and rotation sensing, etc. The magnetometry sensitivity is a key performance of these Rb OPMs which should be improved. In this study, a high sensitivity Rb OPM is demonstrated theoretically and experimentally. To improve the sensitivity, acousto-optic modulation based on balanced detection is applied to suppress the probe noises. Compared with the conventional optical rotation detection for this OPM configuration, the probe noise shows a significant suppression especially in low frequencies. Eventually, a simultaneous dual-axis transverse measurement with 30 fT/Hz1/2 sensitivity is achieved in a 200 Hz bandwidth and a 250nT linear working range. In addition, we utilize a closed-loop feedback to improve the stability and enlarge the transverse measurement range to 10µT order of magnitude while maintain the open-loop performances. A quasi-static magnetic field measurement can also be achieved in the longitudinal direction in the closed-loop mode. This OPM can serve for the nuclear magnetization measurement with a high sensitivity especially in environments with a large magnitude of the external magnetic field.

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12

Lou, Janet W., e Geoffrey A. Cranch. "Optical frequency dependence of the light shift effect for vector magnetometry with cesium". Applied Optics 59, n.º 7 (26 de fevereiro de 2020): 2072. http://dx.doi.org/10.1364/ao.379800.

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LIU, HONG, JIANGUO ZHU e DINGQUAN XIAO. "PREPARATION AND CHARACTERIZATION OF LaFeO3 THIN FILMS ON (100) SrTiO3 SUBSTRATES BY PULSED LASER DEPOSITION". Journal of Advanced Dielectrics 01, n.º 03 (julho de 2011): 363–67. http://dx.doi.org/10.1142/s2010135x11000379.

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A single-crystalline, crack-free, epitaxial (100)c LaFeO3 films were in situ grown by pulsed laser deposition on (100) SrTiO3 substrates. X-ray diffraction, atomic force microscopy and transmission electron microscopy reveal that the LaFeO3 films have high crystalline quality, a very smooth surface, and an atomically sharp LaFeO3/SrTiO3 interface. The magnetic properties of the LaFeO3 films were obtained by a superconducting quantum interference device magnetometry. The saturated magnetization and coercive field of LaFeO3 films are 14 emu/cm3 and 600 Oe, respectively.

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Zhang, Rui, Teng Wu, Jingbiao Chen, Xiang Peng e Hong Guo. "Frequency Response of Optically Pumped Magnetometer with Nonlinear Zeeman Effect". Applied Sciences 10, n.º 20 (10 de outubro de 2020): 7031. http://dx.doi.org/10.3390/app10207031.

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Optically pumped alkali atomic magnetometers based on measuring the Zeeman shifts of the atomic energy levels are widely used in many applications because of their low noise and cryogen-free operation. When alkali atomic magnetometers are operated in an unshielded geomagnetic environment, the nonlinear Zeeman effect may become non-negligible at high latitude and the Zeeman shifts are thus not linear to the strength of the magnetic field. The nonlinear Zeeman effect causes broadening and partial splitting of the magnetic resonant levels, and thus degrades the sensitivity of the alkali atomic magnetometers and causes heading error. In this work, we find that the nonlinear Zeeman effect also influences the frequency response of the alkali atomic magnetometer. We develop a model to quantitatively depict the frequency response of the alkali atomic magnetometer when the nonlinear Zeeman effect is non-negligible and verify the results experimentally in an amplitude-modulated Bell–Bloom cesium magnetometer. The proposed model provides general guidance on analyzing the frequency response of the alkali atomic magnetometer operating in the Earth’s magnetic field. Full and precise knowledge of the frequency response of the atomic magnetometer is important for the optimization of feedback control systems such as the closed-loop magnetometers and the active magnetic field stabilization with magnetometers. This work is thus important for the application of alkali atomic magnetometers in an unshielded geomagnetic environment.

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15

Farfurnik, D., A. Jarmola, D. Budker e N. Bar-Gill. "Spin ensemble-based AC magnetometry using concatenated dynamical decoupling at low temperatures". Journal of Optics 20, n.º 2 (1 de janeiro de 2018): 024008. http://dx.doi.org/10.1088/2040-8986/aaa1bf.

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16

Weis, A., e R. Wynands. "Laser-based precision magnetometry in fundamental and applied research". Optics and Lasers in Engineering 43, n.º 3-5 (março de 2005): 387–401. http://dx.doi.org/10.1016/j.optlaseng.2004.03.010.

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Li, Bei-Bei, Lingfeng Ou, Yuechen Lei e Yong-Chun Liu. "Cavity optomechanical sensing". Nanophotonics 10, n.º 11 (24 de agosto de 2021): 2799–832. http://dx.doi.org/10.1515/nanoph-2021-0256.

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Abstract Cavity optomechanical systems enable interactions between light and mechanical resonators, providing a platform both for fundamental physics of macroscopic quantum systems and for practical applications of precision sensing. The resonant enhancement of both mechanical and optical response in the cavity optomechanical systems has enabled precision sensing of multiple physical quantities, including displacements, masses, forces, accelerations, magnetic fields, and ultrasounds. In this article, we review the progress of precision sensing applications using cavity optomechanical systems. The review is organized in the following way: first we will introduce the physical principles of optomechanical sensing, including a discussion of the noises and sensitivity of the systems, and then review the progress in displacement sensing, mass sensing, force sensing, atomic force microscope (AFM) and magnetic resonance force microscope (MRFM), accelerometry, magnetometry, and ultrasound sensing, and introduce the progress of using quantum techniques especially squeezed light to enhance the performance of the optomechanical sensors. Finally, we give a summary and outlook.

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Jin, Kai, Xuxing Geng, Zhi Liang, Wangwang Tang, Jianfeng Xiao, Heng Hu, Guangming Huang, Gaoxiang Li, Guoqing Yang e Shangqing Liang. "Design of Portable Self-Oscillating VCSEL-Pumped Cesium Atomic Magnetometer". Electronics 11, n.º 22 (9 de novembro de 2022): 3666. http://dx.doi.org/10.3390/electronics11223666.

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With the demand for fast response of magnetic field measurement and the development of laser diode technology, self-oscillating laser-pumped atomic magnetometers have become a new development trend. In this work, we designed a portable self-oscillating VCSEL-pumped Cs atom magnetometer, including the probe (optical path) and circuits. The signal amplification and feedback loop of the magnetometer, VCSEL laser control unit, and atomic cell temperature control unit were realized. We tested the performance of the magnetometer in the metering station. Finally, the performance of the VCSEL-pumped magnetometer designed in this work was compared with that of a CS-3 lamp-pumped self-oscillating atomic magnetometer; their performance was found to be mostly in the same order of magnitude, while the power consumption of our magnetometer was 3 W less than that of the CS-3. This work represents an exploratory attempt to integrate and miniaturize a portable self-oscillating VCSEL-pumped Cs atomic magnetometer.

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Guevara De Jesus, Michael, Zhuyun Xiao, Maite Goiriena-Goikoetxea, Rajesh V. Chopdekar, Mohanchandra K. Panduranga, Paymon Shirazi, Adrian Acosta et al. "Magnetic state switching in FeGa microstructures". Smart Materials and Structures 31, n.º 3 (25 de janeiro de 2022): 035005. http://dx.doi.org/10.1088/1361-665x/ac46db.

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Abstract This work demonstrates that magnetoelectric composite heterostructures can be designed at the length scale of 10 µms that can be switched from a magnetized state to a vortex state, effectively switching the magnetization off, using electric field induced strain. This was accomplished using thin film magnetoelectric heterostructures of Fe81.4Ga18.6 on a single crystal (011) [Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32 (PMN-32PT) ferroelectric substrate. The heterostructures were tripped from a multi-domain magnetized state to a flux closure vortex state using voltage induced strain in a piezoelectric substrate. FeGa heterostructures were deposited on a Si-substrate for superconducting quantum interference device magnetometry characterization of the magnetic properties. The magnetoelectric coupling of a FeGa continuous film on PMN-32PT was characterized using a magneto optical Kerr effect magnetometer with bi-axial strain gauges, and magnetic multi-domain heterostructures were imaged using x-ray magnetic circular dichroism—photoemission electron microscopy during the transition to the vortex state. The domain structures were modelled using MuMax3, a micromagnetics code, and compared with observations. The results provide considerable insight into designing magnetoelectric heterostructures that can be switched from an ‘on’ state to an ‘off’ state using electric field induced strain.

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Zamani, Amin, Maliheh Ranjbaran, Mohammad Mehdi Tehranchi, Seyedeh Mehri Hamidi e Seyed Mohammad Hosein Khalkhali. "Myocardial Ischemia Detection by a Sensitive Pump-Probe Atomic Magnetometer". Journal of Lasers in Medical Sciences 13, n.º 1 (26 de maio de 2022): e24-e24. http://dx.doi.org/10.34172/jlms.2022.24.

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Introduction: Magnetocardiography (MCG) based on optical atomic magnetometers has shown promise for detecting heart diseases accurately. Different methods were introduced to improve the sensitivity of detecting magnetic fields during cardiac activity. Methods: In this paper, an optical pump-probe magnetometer operated on the ground-state Hanle effect based on the zero-field level crossing technique was developed and the laser output signal was optimized in an unshielded environment. Then, the optical magnetometer was utilized to record the simulated MCG trace of different stages of myocardial ischemia. Results: The probe output light intensity followed the variation of cardiac magnetic field (MCG trace) generated by Helmholtz coil accurately. Conclusion: Based on the results, the feasibility of our highly sensitive optical magnetometer in tracing showed no change in the P-QRS-T waveform associated with ischemic heart disease (IHD), where P indicates atrial depolarization, QRS is responsible for ventricular depolarization, and T represents ventricular repolarization.

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Lu, Jixi, Jing Wang, Ke Yang, Junpeng Zhao, Wei Quan, Bangcheng Han e Ming Ding. "In-Situ Measurement of Electrical-Heating-Induced Magnetic Field for an Atomic Magnetometer". Sensors 20, n.º 7 (25 de março de 2020): 1826. http://dx.doi.org/10.3390/s20071826.

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Electrical heating elements, which are widely used to heat the vapor cell of ultrasensitive atomic magnetometers, inevitably produce a magnetic field interference. In this paper, we propose a novel measurement method of the amplitude of electrical-heating-induced magnetic field for an atomic magnetometer. In contrast to conventional methods, this method can be implemented in the atomic magnetometer itself without the need for extra magnetometers. It can distinguish between different sources of magnetic fields sensed by the atomic magnetometer, and measure the three-axis components of the magnetic field generated by the electrical heater and the temperature sensor. The experimental results demonstrate that the measurement uncertainty of the heater’s magnetic field is less than 0.2 nT along the x-axis, 1.0 nT along the y-axis, and 0.4 nT along the z-axis. The measurement uncertainty of the temperature sensor’s magnetic field is less than 0.02 nT along all three axes. This method has the advantage of measuring the in-situ magnetic field, so it is especially suitable for miniaturized and chip-scale atomic magnetometers, where the cell is extremely small and in close proximity to the heater and the temperature sensor.

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Lee, Hyunjoon, Kiwoong Kim, Seong-Joo Lee, Chan-Seok Kang, Kwon Kyu Yu, Yong-Ho Lee e Han Seb Moon. "Development of spin-exchange relaxation free magnetometer with a compact heating system". ACTA IMEKO 2, n.º 1 (16 de agosto de 2013): 16. http://dx.doi.org/10.21014/acta_imeko.v2i1.46.

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Atomic magnetometers based on spin-exchange relaxation free (SERF) regime typically operate with the high optical density and low magnetic fields. We present SERF magnetometer with a compact heating system for compact and efficient temperature control. A resistive heating system with high frequency alternating current was used to achieve high optical density. The current frequency was carefully chosen to avoid resonance with the atomic magnetometer. This resulted in a compact heating system that also allows independent operation of multiple heating systems. Optical rotation signal was obtained at 200 oC and width was about 3 nT with pump laser power of 55 mW. Bandwidth of the magnetometer with the compact heater was 40 Hz. Consequently, the compact resistive heating system proved to be a good alternative to the air-flow heating system. Additionally, residual field effect and signal-to-noise yielded a sensitivity of 50 fT/Hz1/2 at 10 Hz.

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Duò, L., M. Marcon e F. Ciccacci. "Input electron optics for Mott detectors used in secondary electron magnetometry". Journal of Electron Spectroscopy and Related Phenomena 95, n.º 2-3 (outubro de 1998): 255–60. http://dx.doi.org/10.1016/s0368-2048(98)00250-3.

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Masuyama, Yuta, Katsumi Suzuki, Akira Hekizono, Mitsuyasu Iwanami, Mutsuko Hatano, Takayuki Iwasaki e Takeshi Ohshima. "Gradiometer Using Separated Diamond Quantum Magnetometers". Sensors 21, n.º 3 (2 de fevereiro de 2021): 977. http://dx.doi.org/10.3390/s21030977.

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The negatively charged nitrogen-vacancy (NV) center in diamonds is known as the spin defect and using its electron spin, magnetometry can be realized even at room temperature with extremely high sensitivity as well as a high dynamic range. However, a magnetically shielded enclosure is usually required to sense weak magnetic fields because environmental magnetic field noises can disturb high sensitivity measurements. Here, we fabricated a gradiometer with variable sensor length that works at room temperature using a pair of diamond samples containing negatively charged NV centers. Each diamond is attached to an optical fiber to enable free sensor placement. Without any magnetically shielding, our gradiometer realizes a magnetic noise spectrum comparable to that of a three-layer magnetically shielded enclosure, reducing the noises at the low-frequency range below 1 Hz as well as at the frequency of 50 Hz (power line frequency) and its harmonics. These results indicate the potential of highly sensitive magnetic sensing by the gradiometer using the NV center for applications in noisy environments such as outdoor and in vehicles.

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Matthews, A. J., J. P. Watts, M. Zhu, A. Usher, M. Elliott, W. G. Herrenden-Harker, P. R. Morris, M. Y. Simmons e D. A. Ritchie. "Current breakdown of the integer and fractional quantum Hall effects detected by torque magnetometry". Physica E: Low-dimensional Systems and Nanostructures 6, n.º 1-4 (fevereiro de 2000): 140–43. http://dx.doi.org/10.1016/s1386-9477(99)00079-x.

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Zeng, Xian Jin, Mo Si Hao, Qing Meng Li, Qiang Liu, Jun Hai Zhang e Wei Min Sun. "A Design of Cesium Atomic Magnetometer Based on Circular Dichroism". Applied Mechanics and Materials 203 (outubro de 2012): 268–72. http://dx.doi.org/10.4028/www.scientific.net/amm.203.268.

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Recently, atomic magnetometers have been reported as the most sensitive magnetometers by completely eliminating the spin exchange relaxation. In this paper, we described a design of highly sensitive cesium atomic magnetometer based on circular dichroism, which had the advantage of easily locking the probing laser to the necessary frequency compared with those based on circular birefringence. In order to polarize the cesium atoms uniformly, the pumping laser light was separated into two counter-propagating and counter-circular polarization beams through the atomic vapor cell. We employed a circular analyzer optical configuration to measure the ellipticity of the probing light, which indicated the amplitude of the magnetic field. The external magnetic field was tracked by a digital auto frequency tracking system.

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Mihailovic, Pedja, e Slobodan Petricevic. "Fiber Optic Sensors Based on the Faraday Effect". Sensors 21, n.º 19 (30 de setembro de 2021): 6564. http://dx.doi.org/10.3390/s21196564.

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Some 175 years ago Michael Faraday discovered magnetic circular birefringence, now commonly known as the Faraday effect. Sensing the magnetic field through the influence that the field has on light within the fiber optic sensor offers several advantages, one of them fundamental. These advantages find application in the measurement of electric current at high voltages by measuring the induced magnetic field, thus warranting application for this kind of fiber optic sensor (FOS) in future smart grids. Difficulties in designing and manufacturing high-performance FOSs were greatly alleviated by developments in optical telecommunication technology, thus giving new impetus to magnetometry based on the Faraday effect. Some of the major problems in the processing of optical signals and temperature dependence have been resolved, yet much effort is still needed to implement all solutions into a single commercial device. Artificial structures with giant Faraday rotation, reported in the literature in the 21st century, will further improve the performance of FOSs based on the Faraday effect. This paper will consider obstacles and limits imposed by the available technology and review solutions proposed so far for fiber optic sensors based on the Faraday effect.

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Вершовский, А. К., С. П. Дмитриев, Г. Г. Козлов, А. С. Пазгалев e М. В. Петренко. "Проекционный спиновый шум в оптических квантовых датчиках на тепловых атомах". Журнал технической физики 90, n.º 8 (2020): 1243. http://dx.doi.org/10.21883/jtf.2020.08.49533.438-19.

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The paper theoretically and experimentally investigates the fundamental limitations imposed by spin (or atomic) quantum projection noise on the sensitivity of optical quantum sensors based on thermal atoms (this class of devices includes frequency standards, magnetometers, and gyroscopes using optical detection of electron paramagnetic resonance). The effect of increasing the rms amplitude of the projection noise in the magnetometric scheme under the influence of strong optical pumping is demonstrated, its explanation is proposed and experimentally tested - it is shown that in a wide range of pump intensities this effect is explained by the invariance of the projection noise integral power with respect to the magnetic resonance line width. An experimental study of the parameters of projection noise in a magnetometric quantum sensor was carried out, recommendations were given for optimizing the sensor parameters.

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Ma, Yintao, Zhixia Qiao, Mingzhi Yu, Yanbin Wang, Yao Chen, Guoxi Luo, Ping Yang et al. "Single-beam integrated hybrid optical pumping spin exchange relaxation free magnetometer for biomedical applications". Applied Physics Letters 121, n.º 11 (12 de setembro de 2022): 114001. http://dx.doi.org/10.1063/5.0105945.

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An ingenious approach to accomplish the high signal strengthen and relatively homogeneous spin polarization has been presented in a hybrid optical pumping spin-exchange-relaxation-free atomic magnetometer only utilizing single-beam configuration. We have experimentally demonstrated an approximately three-fold enhancement of the output signal at the optimal spin polarization by optically pumping the thin vapor due to the same spin evolution behavior of the two different kinds of vapor atoms. Eventually, a measuring sensitivity of 30 fT/Hz1/2 was achieved combined with the homemade differential detection system for attenuating large background offset and suppressing optical power noise. This scheme provides a prospect for the development of ultra-highly sensitive and chip-scale atomic magnetometer for the applications that desire both high signal-to-noise ratio and uniform spin polarization, such as magnetocardiography and magnetoencephalography.

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Mu, Jiliang, Zhang Qu, Zongmin Ma, Shaowen Zhang, Yunbo Shi, Jian Gao, Xiaoming Zhang et al. "Ensemble spin fabrication and manipulation of NV centres for magnetic sensing in diamond". Sensor Review 37, n.º 4 (18 de setembro de 2017): 419–24. http://dx.doi.org/10.1108/sr-09-2016-0163.

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Purpose This study aims to fabricate and manipulate ensemble spin of negative nitrogen-vacancy (NV−) centres optimally for future solid atomic magnetometers/gyroscope. Parameters for sample preparation most related to magnetometers/gyroscope are, in particular, the concentration and homogeneity of the NV− centres, the parameters’ microwave antenna of resonance frequency and the strength of the microwave on NV− centres. Besides, the abundance of other impurities such as neutral NV centres (NV0) and substitutional nitrogen in the lattice also plays a critical role in magnetic sensing. Design/methodology/approach The authors succeeded in fabricating the assembly of NV centres in diamond and they determined its concentration of (2-3) × 1016 cm−3 with irradiation followed by annealing under a high temperature condition. They explored a novel magnetic resonance approach to detect the weak magnetic fields that takes advantage of the solid-state electron ensemble spin of NV− centres in diamond. In particular, the authors set up a magnetic sensor on the basis of the assembly of NV centres. They succeeded in fabricating the assembly of NV centres in diamond and determined its concentration. They also clarified the magnetic field intensity measured at different positions along the antenna with different lengths, and they found the optimal position where the signal of the magnetic field reaches the maximum. Findings The authors mainly reported preparation, initialization, manipulation and measurement of the ensemble spin of the NV centres in diamond using optical excitation and microwave radiation methods with variation of the external magnetic field. They determined the optimal parameters of irradiation and annealing to generate the ensemble NV centres, and a concentration of NV− centres as high as 1016 cm−3 in diamond was obtained. In addition, they found that sensitivity of the magnetometer using this method can reach as low as 5.22 µT/Hz currently. Practical implications This research can shed light on the development of an atomic magnetometer and a gyroscope on the basis of the ensemble spin of NV centres in diamond. Social implications High concentration spin of NV− in diamond is one of the advantages compared with that of the atomic vapor cells, because it can obtain a higher concentration. When increasing the spin concentration, the spin signal is easy to detect, and macro-atomic spin magnetometer become possible. This research is the first step for solid atomic magnetometers with high spin density and high sensitivity potentially with further optimization. It has a wide range of applications from fundamental physics tests, sensor applications and navigation to detection of NMR signals. Originality/value As has been pointed out, in this research, the authors mainly worked on fabricating NV− centres with high concentration (1015-1016 cm−3) in diamond by using optimal irradiation and annealing processes, and they quantitatively defined the NV− concentration, which is important for the design of higher concentration processes in the magnetometer and gyroscope. Until now, few groups can directly define the NV− concentration. Besides, the authors optimized the microwave antenna parameters experimentally and explored the dependence between the splitting of the magnetic resonance and the magnetic fields, which dictated the minimum detectable magnetic field.

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Jain, Megha, Manju, Pargam Vashishtha, Govind Gupta, Anil Kumar Sinha, Mukul Gupta, Ankush Vij e Anup Thakur. "Mechanistic insights into defect generation and tuning of optical properties in Zn1−x Fe x Al2O4(0.01 ≤ x ≤ 0.40) nanocrystals". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 76, n.º 5 (15 de agosto de 2020): 757–68. http://dx.doi.org/10.1107/s2052520620009130.

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The correlation of several defects and optical and magnetic properties with Fe content in Zn1−x Fe x Al2O4 (0.01 ≤ x ≤ 0.40) nanocrystals has been scrutinized through X-ray diffraction, O K-edge X-ray absorption near-edge structure, FT–IR, diffuse reflectance, photoluminescence and electron spin-resonance spectroscopies, and vibrating sample magnetometry. Increasing Fe content causes elongation in the octahedral units of the lattice, accompanied by distortion in the octahedral coordination. Fe introduces non-radiative centres in the forbidden gap, thereby tuning the band gap from 4.37 to 3.88 eV and eliminating emission in the visible region. Zn vacancies are found to tail off, while {\rm Fe}_i^{\bullet \bullet \bullet}, {\rm Al}_{\rm Zn}^\bullet and FeAl × antisite defects increase in concentration with increasing Fe content. Inhomogeneous broadening of spin-resonance signals infers strong spin-lattice interactions of Fe3+ ions at distorted octahedral and non-symmetric tetrahedral sites. A transition is observed from paramagnetism to superparamagnetism at higher Fe concentrations. A visual colour change from pearly white to orange–brown is observed in Zn1−x Fe x Al2O4 nanocrystals with increasing Fe content, revealing its potential candidature for pigments in the paint and dye industries.

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Bennett, James S., Brian E. Vyhnalek, Hamish Greenall, Elizabeth M. Bridge, Fernando Gotardo, Stefan Forstner, Glen I. Harris, Félix A. Miranda e Warwick P. Bowen. "Precision Magnetometers for Aerospace Applications: A Review". Sensors 21, n.º 16 (18 de agosto de 2021): 5568. http://dx.doi.org/10.3390/s21165568.

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Aerospace technologies are crucial for modern civilization; space-based infrastructure underpins weather forecasting, communications, terrestrial navigation and logistics, planetary observations, solar monitoring, and other indispensable capabilities. Extraplanetary exploration—including orbital surveys and (more recently) roving, flying, or submersible unmanned vehicles—is also a key scientific and technological frontier, believed by many to be paramount to the long-term survival and prosperity of humanity. All of these aerospace applications require reliable control of the craft and the ability to record high-precision measurements of physical quantities. Magnetometers deliver on both of these aspects and have been vital to the success of numerous missions. In this review paper, we provide an introduction to the relevant instruments and their applications. We consider past and present magnetometers, their proven aerospace applications, and emerging uses. We then look to the future, reviewing recent progress in magnetometer technology. We particularly focus on magnetometers that use optical readout, including atomic magnetometers, magnetometers based on quantum defects in diamond, and optomechanical magnetometers. These optical magnetometers offer a combination of field sensitivity, size, weight, and power consumption that allows them to reach performance regimes that are inaccessible with existing techniques. This promises to enable new applications in areas ranging from unmanned vehicles to navigation and exploration.

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Jun-xiang ZHAO, 赵俊祥, 左冠华 Guan-hua ZUO, 李静 Jing LI, 张玉驰 Yu-chi ZHANG, 张鹏飞 Peng-fei ZHANG e 张天才 Tian-cai ZHANG. "基于腔增强的磁光旋转铯原子磁强计". Acta Sinica Quantum Optica 27, n.º 3 (2021): 192. http://dx.doi.org/10.3788/jqo20212703.0201.

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Zhang, Rui, Wei Xiao, Yudong Ding, Yulong Feng, Xiang Peng, Liang Shen, Chenxi Sun et al. "Recording brain activities in unshielded Earth’s field with optically pumped atomic magnetometers". Science Advances 6, n.º 24 (junho de 2020): eaba8792. http://dx.doi.org/10.1126/sciadv.aba8792.

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Understanding the relationship between brain activity and specific mental function is important for medical diagnosis of brain symptoms, such as epilepsy. Magnetoencephalography (MEG), which uses an array of high-sensitivity magnetometers to record magnetic field signals generated from neural currents occurring naturally in the brain, is a noninvasive method for locating the brain activities. The MEG is normally performed in a magnetically shielded room. Here, we introduce an unshielded MEG system based on optically pumped atomic magnetometers. We build an atomic magnetic gradiometer, together with feedback methods, to reduce the environment magnetic field noise. We successfully observe the alpha rhythm signals related to closed eyes and clear auditory evoked field signals in unshielded Earth’s field. Combined with improvements in the miniaturization of the atomic magnetometer, our method is promising to realize a practical wearable and movable unshielded MEG system and bring new insights into medical diagnosis of brain symptoms.

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Li, Guozhu, Qing Xin, Xuxing Geng, Zhi Liang, Shangqing Liang, Guangming Huang, Gaoxiang Li e Guoqing Yang. "Current sensor based on an atomic magnetometer for DC application". Chinese Optics Letters 18, n.º 3 (2020): 031202. http://dx.doi.org/10.3788/col202018.031202.

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Akhmedzhanov, R. A., L. A. Gushchin, I. V. Zelensky, V. A. Nizov, N. A. Nizov e D. A. Sobgaida. "Application of polycrystalline diamonds for magnetometry based on interactions of nonequivalently oriented groups of NV centres". Quantum Electronics 48, n.º 10 (31 de outubro de 2018): 912–15. http://dx.doi.org/10.1070/qel16759.

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Yan, Yeguang, Jixi Lu, Binquan Zhou, Kun Wang, Ziao Liu, Xiaoyu Li, Weiyi Wang e Gang Liu. "Analysis and Correction of the Crosstalk Effect in a Three-Axis SERF Atomic Magnetometer". Photonics 9, n.º 9 (14 de setembro de 2022): 654. http://dx.doi.org/10.3390/photonics9090654.

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Three-axis atomic magnetometers have an excellent advantage for determining the complete vector information of a magnetic field to be measured. However, the crosstalk effect, which leads to an error output on one axis owing to a magnetic field on the other axes, can reduce the measurement accuracy. In this study, we propose an effective suppression method for the crosstalk effect in a three-axis atomic magnetometer. First, we investigated and analyzed the main factors that introduce the effect. Based on this, the modulation parameters were optimized to improve the scale factors, which obtained a coupling coefficient of less than 6.00% for the atomic magnetometer. Subsequently, the associated transfer matrix was corrected to further suppress the crosstalk effect. After correction, all the coupling coefficients were decreased to less than 3.00%, with the majority being lower than 1.00%.

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Long, Dafeng, Xiaoming Zhang, Xiaohui Wei, Zhongliang Luo e Jianzhong Cao. "A Fast Calibration and Compensation Method for Magnetometers in Strap-Down Spinning Projectiles". Sensors 18, n.º 12 (27 de novembro de 2018): 4157. http://dx.doi.org/10.3390/s18124157.

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Attitude measurement is an essential technology in projectile trajectory correction. Magnetometers have been used for projectile attitude measurement systems as they are small in size, lightweight, and low cost. However, magnetometers are seriously disturbed by the artillery magnetic field during launch. Moreover, the error parameters of the magnetometers, which are calibrated in advance, usually change after extended storage. The changed parameters have negative effects on attitude estimation of the projectile. To improve the accuracy of attitude estimation, the magnetometers should be calibrated again before launch or during flight. This paper presents a fast calibration method specific for a spinning projectile. At the launch site, the tri-axial magnetometer is calibrated, the parameters of magnetometer are quickly obtained by optimal ellipsoid fitting based on a least squares criterion. Then, the calibration parameters are used to compensate for magnetometer outputs during flight. The numerical simulation results show that the proposed calibration method can effectively determine zero bias, scale factors, and alignment angle errors. Finally, a semi-physical experimental system was designed to further verify the performance of the calibration method. The results show that pitch angle error reduces from 3.52° to 0.58° after calibration. The roll angle error is reduced from 2.59° to 0.65°. Simulations and experimental results indicate that the accuracy of magnetometer in strap-down spinning projectile has been greatly enhanced, and the attitude estimation errors are reduced after calibration.

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Li Shu-Guang, Zhou Xiang, Cao Xiao-Chao, Sheng Ji-Teng, Xu Yun-Fei, Wang Zhao-Ying e Lin Qiang. "All-optical high sensitive atomic magnetometer". Acta Physica Sinica 59, n.º 2 (2010): 877. http://dx.doi.org/10.7498/aps.59.877.

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Thormählen, Lars, Dennis Seidler, Viktor Schell, Frans Munnik, Jeffrey McCord e Dirk Meyners. "Sputter Deposited Magnetostrictive Layers for SAW Magnetic Field Sensors". Sensors 21, n.º 24 (15 de dezembro de 2021): 8386. http://dx.doi.org/10.3390/s21248386.

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For the best possible limit of detection of any thin film-based magnetic field sensor, the functional magnetic film properties are an essential parameter. For sensors based on magnetostrictive layers, the chemical composition, morphology and intrinsic stresses of the layer have to be controlled during film deposition to further control magnetic influences such as crystallographic effects, pinning effects and stress anisotropies. For the application in magnetic surface acoustic wave sensors, the magnetostrictive layers are deposited on rotated piezoelectric single crystal substrates. The thermomechanical properties of quartz can lead to undesirable layer stresses and associated magnetic anisotropies if the temperature increases during deposition. With this in mind, we compare amorphous, magnetostrictive FeCoSiB films prepared by RF and DC magnetron sputter deposition. The chemical, structural and magnetic properties determined by elastic recoil detection, X-ray diffraction, and magneto-optical magnetometry and magnetic domain analysis are correlated with the resulting surface acoustic wave sensor properties such as phase noise level and limit of detection. To confirm the material properties, SAW sensors with magnetostrictive layers deposited with RF and DC deposition have been prepared and characterized, showing comparable detection limits below 200 pT/Hz1/2 at 10 Hz. The main benefit of the DC deposition is achieving higher deposition rates while maintaining similar low substrate temperatures.

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Liu, Qiang, Yu Dan Sun, Qiang Huang, Xian Jin Zeng, Jun Hai Zhang e Wei Min Sun. "Measurement of Linearly Polarized Light Rotation Applied in Atomic Magnetometer". Advanced Materials Research 753-755 (agosto de 2013): 2149–52. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.2149.

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The measurement of linearly polarized light rotation is the key technique in atomic magnetometer. It influences the sensitivity of atomic magnetometer directly. The basic principle of polarizer beam splitter detecting was analyzed. The ZF7 optical glass and solenoid were used to generate standard small angle based on Faraday effect. The signal of AC rotational angle was extracted by lock-in amplifier. The experiment proved that the method can measure 8×10-7rad small optical rotation. As the linearly polarized light rotation is 20mrad in atomic magnetometer, the signal to noise ratio reaches 25000.

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Hong, Hyun-Gue, Sang Eon Park, Sang-Bum Lee, Myoung-Sun Heo, Jongcheol Park, Tae Hyun Kim, Hee Yeon Kim e Taeg Yong Kwon. "Chip-Scale Ultra-Low Field Atomic Magnetometer Based on Coherent Population Trapping". Sensors 21, n.º 4 (22 de fevereiro de 2021): 1517. http://dx.doi.org/10.3390/s21041517.

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We report a chip-scale atomic magnetometer based on coherent population trapping, which can operate near zero magnetic field. By exploiting the asymmetric population among magnetic sublevels in the hyperfine ground state of cesium, we observe that the resonance signal acquires sensitivity to magnetic field in spite of degeneracy. A dispersive signal for magnetic field discrimination is obtained near-zero-field as well as for finite fields (tens of micro-tesla) in a chip-scale device of 0.94 cm3 volume. This shows that it can be readily used in low magnetic field environments, which have been inaccessible so far in miniaturized atomic magnetometers based on coherent population trapping. The measured noise floor of 300 pT/Hz1/2 at the zero-field condition is comparable to that of the conventional finite-field measurement obtained under the same conditions. This work suggests a way to implement integrated atomic magnetometers with a wide operating range.

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Biryukov, Yaroslav P., Almaz L. Zinnatullin, Mikhail A. Cherosov, Andrey P. Shablinskii, Roman V. Yusupov, Rimma S. Bubnova, Farit G. Vagizov, Stanislav K. Filatov, M. S. Avdontceva e Igor V. Pekov. "Low-temperature investigation of natural iron-rich oxoborates vonsenite and hulsite: thermal deformations of crystal structure, strong negative thermal expansion and cascades of magnetic transitions". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 77, n.º 6 (26 de novembro de 2021): 1021–34. http://dx.doi.org/10.1107/s2052520621010866.

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This work is devoted to an investigation of the magnetic properties and thermal behaviour of the natural oxoborates vonsenite and hulsite in the temperature range 5–500 K. The local environment, the oxidation states of the Fe and Sn atoms, and the charge distribution were determined using Mössbauer spectroscopy and are in accordance with a refinement of the crystal structure of hulsite from single-crystal X-ray diffraction data (SCXRD) in anisotropic approximation for the first time. The magnetic properties were studied by vibrating sample magnetometry (VSM) (5 ≤ T ≤ 400 K) and are reported for the first time for iron-rich hulsite. Both oxoborates show a very complex magnetic behaviour. Cascades of magnetic transitions are revealed and the critical temperatures were determined. The sequences of magnetic transitions in both vonsenite and hulsite with increasing temperature were found to be as follows: magnetically ordered state → partial magnetic ordering → paramagnetic state. According to X-ray diffraction data (93 ≤ T ≤ 500 K), these processes are accompanied by anomalies in the unit-cell parameters and thermal expansion of the oxoborates at critical temperatures. A strong negative volume thermal expansion is observed for both oxoborates at temperatures below ∼120 K.

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Lu, Fei, Shuying Wang, Nuozhou Xu, Bo Li, Jixi Lu e Bangcheng Han. "Analysis and Suppression of the Cross-Axis Coupling Effect for Dual-Beam SERF Atomic Magnetometer". Photonics 9, n.º 11 (25 de outubro de 2022): 792. http://dx.doi.org/10.3390/photonics9110792.

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Spin-exchange relaxation-free (SERF) atomic magnetometers operated under a near-zero magnetic field are used for vector magnetic field measurements with high sensitivity. Previously, the cross-axis coupling error evoked by a nonzero background magnetic field has been verified to be adverse in modulated single-beam magnetometers. Here, in a dual-beam unmodulated SERF magnetometer, we propose a somewhat different solution model for the cross-axis coupling effect where the field of interest couples with the interference field. Considering two cases where the transverse or longitudinal background field exists, the cross-axis coupling effect dependence on multiple factors is investigated here based on the dynamic response under a background magnetic field within ±5 nT. The theoretical and experimental investigation suggests that it has an adverse impact on the output response amplitude and phase and tilts the sensitive axis by several degrees, causing a measurement error on the dual-beam magnetometer. To suppress this effect, the background magnetic field is compensated through the PI closed-loop control. The coupling effect is effectively suppressed by 1.5 times at the 10–40 Hz low-frequency band and the sensitivity reaches 2.4 fT/Hz1/2.

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Rosner, M., D. Beck, P. Fierlinger, H. Filter, C. Klau, F. Kuchler, P. Rößner, M. Sturm, D. Wurm e Z. Sun. "A highly drift-stable atomic magnetometer for fundamental physics experiments". Applied Physics Letters 120, n.º 16 (18 de abril de 2022): 161102. http://dx.doi.org/10.1063/5.0083854.

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We report the design and performance of a nonmagnetic drift stable optically pumped cesium magnetometer with a measured sensitivity of 35 fT at 200 s integration time and stability below 50 fT between 70 and 600 s. The sensor is based on the nonlinear magneto-optical rotation effect: in a Bell–Bloom configuration, a higher order polarization moment (alignment) of Cs atoms is created with a pump laser beam in an anti-relaxation coated Pyrex cell under vacuum, filled with Cs vapor at room temperature. The polarization plane of light passing through the cell is modulated due the precession of the atoms in an external magnetic field of 2.1 μT, used to optically determine the Larmor precession frequency. Operation is based on a sequence of optical pumping and observation of freely precessing spins at a repetition rate of 8 Hz. This free precession decay readout scheme separates optical pumping and probing and, thus, ensures a systematically highly clean measurement. Due to the residual offset of the sensor of <15 pT together with negligible crosstalk of adjacent sensors, this device is uniquely suitable for a variety of experiments in low-energy particle physics with extreme precision, here as a highly stable and systematically clean reference probe in search for time-reversal symmetry violating electric dipole moments.

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Higbie, J. M., E. Corsini e D. Budker. "Robust, high-speed, all-optical atomic magnetometer". Review of Scientific Instruments 77, n.º 11 (novembro de 2006): 113106. http://dx.doi.org/10.1063/1.2370597.

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Hutanu, Vladimir, Hao Deng, Sheng Ran, Wesley T. Fuhrman, Henrik Thoma e Nicholas P. Butch. "Low-temperature crystal structure of the unconventional spin-triplet superconductor UTe2 from single-crystal neutron diffraction". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 76, n.º 1 (29 de janeiro de 2020): 137–43. http://dx.doi.org/10.1107/s2052520619016950.

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The crystal structure of a new superconductor UTe2 has been investigated using single-crystal neutron diffraction for the first time at the low temperature (LT) of 2.7 K, just above the superconducting transition temperature of ∼1.6 K, in order to clarify whether the orthorhombic structure of type Immm (No. 71), reported for the room-temperature (RT) structure persists down to the superconducting phase and can be considered as a parent symmetry for the development of spin-triplet superconductivity. In contrast to the previously reported phase transition at about 100 K [Stöwe (1996). J. Solid State Chem. 127, 202–210], our high-precision LT neutron diffraction data show that the body-centred RT symmetry is indeed maintained down to 2.7 K. No sign of a structural change from RT down to 2.7 K was observed. The most significant change depending on temperature was observed for the U ion position and the U–U distance along the c direction, implying its potential importance as a magnetic interaction path. No magnetic order could be deduced from the neutron diffraction data refinement at 2.7 K, consistent with bulk magnetometry. Assuming normal thermal evolution of the lattice parameters, moderately large linear thermal expansion coefficients of about α = 2.8 (7) × 10−5 K−1 are estimated.

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Liu, Qiang, Yu Dan Sun, Yan Nan Zhuo, Jia Xing Wang e Tian Shu Fu. "Influence of He Buffer Gas Pressure on Cs Atomic Polarizability". Applied Mechanics and Materials 475-476 (dezembro de 2013): 173–76. http://dx.doi.org/10.4028/www.scientific.net/amm.475-476.173.

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All optical cesium (Cs) atomic magnetometer with high sensitivity is an important technique to detect weak magnetic field. The Cs vapor cell is filled with He buffer gas to reduce spin relaxation rate. However the pressure of He also influences the Cs atomic polarizability due to pressure broadening effect. In this work, the principle of all optical Cs atomic magnetometer is analyzed. The rate equation is used to calculate Cs atomic polarizability as the pressure of He is about 100Torr and pure Cs vapor cell. The calculation shows that higher pressure of He buffer gas can decrease Cs atomic polarizability without considering spin-exchange collisions, as the pump beam frequency is locked to Cs D1 transition F=3F=4.

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Amorós-Binefa, Júlia, e Jan Kołodyński. "Noisy atomic magnetometry in real time". New Journal of Physics 23, n.º 12 (1 de dezembro de 2021): 123030. http://dx.doi.org/10.1088/1367-2630/ac3b71.

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Abstract Continuously monitored atomic spin-ensembles allow, in principle, for real-time sensing of external magnetic fields beyond classical limits. Within the linear-Gaussian regime, thanks to the phenomenon of measurement-induced spin-squeezing, they attain a quantum-enhanced scaling of sensitivity both as a function of time, t, and the number of atoms involved, N. In our work, we rigorously study how such conclusions based on Kalman filtering methods change when inevitable imperfections are taken into account: in the form of collective noise, as well as stochastic fluctuations of the field in time. We prove that even an infinitesimal amount of noise disallows the error to be arbitrarily diminished by simply increasing N, and forces it to eventually follow a classical-like behaviour in t. However, we also demonstrate that, ‘thanks’ to the presence of noise, in most regimes the model based on a homodyne-like continuous measurement actually achieves the ultimate sensitivity allowed by the decoherence, yielding then the optimal quantum-enhancement. We are able to do so by constructing a noise-induced lower bound on the error that stems from a general method of classically simulating a noisy quantum evolution, during which the stochastic parameter to be estimated—here, the magnetic field—is encoded. The method naturally extends to schemes beyond the linear-Gaussian regime, in particular, also to ones involving feedback or active control.

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Wang, Bowen, Xiang Peng, Haidong Wang, Wei Xiao e Hong Guo. "All-Optical Parametric-Resonance Magnetometer Based on 4He Atomic Alignment". Sensors 22, n.º 11 (31 de maio de 2022): 4184. http://dx.doi.org/10.3390/s22114184.

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Parametric-resonance magnetometer is a high-sensitivity quantum sensor characterized by applying the non-resonant radio-frequency (RF) fields to the atomic ensemble. The RF fields lead to crosstalk in the multi-sensor design, thus disturbing the magnetic-field measurement results. We propose an optically modulated alignment-based 4He parametric-resonance magnetometer. By using the fictitious field generated by the modulated light shift, parametric resonance is realized, and crosstalk caused by the magnetic RF field is prevented. The relative intensity noise of the lasers is suppressed to optimize the sensitivity of the magnetometer. Our magnetometer experimentally demonstrates a magnetic-field noise floor of 130 fT/Hz1/2 in both open- and closed-loop operations and has the potential to reach 70 fT/Hz1/2 when compared with the optimized magnetic RF scheme. It provides near-zero magnetic-field measurements with a 2 kHz bandwidth at room temperature, which is useful for high-bandwidth measurements in biomagnetic applications.

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